<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>NaN</title>
</head>
<body>
    <script>
        console.log(NaN);//Not a Number
        console.log(typeof NaN);//number
        console.log(0/0,6/0,-6/0);//NaN,Infinity,-Infinity
        console.log(Math.sqrt(-1));//NaN
        console.log("abc"-10);//NaN
        console.log(undefined+10);//NaN
        console.log(parseInt("Hello"));//NaN
        const a=0/0;
        const b=parseInt("hello");
        if(Number.isNaN(parseInt("hello"))){
            console.log("hello不是一个数字");
        }
    </script>
</body>
</html>